Estimation of physiological sources of nonlinearity in blood oxygenation level-dependent contrast signals
Daehun Kang1, Yul-Wan Sung2, Satoshi Shioiri3
1Kansei Fukushi Research Institute, Tohoku Fukushi University, Sendai, Japan; Graduate School of Information Sciences and Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
Abstract:
Blood oxygenation level-dependent (BOLD) contrast appears through a variation in the transverse relaxation rate of magnetic resonance signals induced by neurovascular coupling and is known to have nonlinear characteristics along echo time (TE) due to the intra-vasculature. However, the physiological causes of this nonlinearity are unclear. We attempted to estimate the physiological information related to the nonlinearity of BOLD signals by using a two-compartment model. For this purpose, we used a multi-echo gradient-echo echo-planar imaging sequence and developed a computational method to estimate the physiological information from the TE-dependent BOLD signals. The results showed that the average chemical exchange time in the intra-vasculature varied during stimulation, which might be the essential source of the nonlinearity.
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